Check your CO. Most of them state very clearly how far a parent can move without having to get permission. Over all as long as she isn't trying to change the school district and is still holding up her end of transportation it might not be worth fighting over.

She moved she makes up the difference in travel.

It also depends on the state. In my state, it's in state law that a parent cannot move a child out of a school district without providing written notice to the other parent. The second parent has so many days to object to the move. It's written into the state law, so it supercedes any parenting plan (I assume most parenting plans in the state - like my DH's - include the legal citation in sections about custodial parent moves.